Almost everyone would agree it is far easier to argue on behalf of Apple than it is to examine the company and question its future.

But stocks are bought not for what a company has accomplished, but what a company plans to do tomorrow.

Fundamental business decisions like new products matter. And stock performance is all about sales and earnings and, most important, future sales and earnings — forecasts of corporate performance.

Perhaps that’s why investors have Apple trading at a below-market-price multiple of just 15 times earnings. By comparison, other major technology leaders like Facebook and Netflix trade at 93 and 251 times earnings, respectively.

Apple’s isn’t an A+ valuation for a firm growing at more than 30 percent.

Perhaps the market is predicting that while Apple has numerous products — iTunes, Music, iPads, Macs and Watches — it is essentially a one-trick company, with 63 percent of sales coming from the iPhone 6 alone.

It was an underwhelming sales number in iPhones that knocked the stock down more than 4 percent on Wednesday. As great a smartphone as the iPhone is, it does leave Apple vulnerable if the company doesn’t adapt.

The stock has been a great buy and hold for many years. But what would be the fundamental business signs or “tells” you should look for to see if Apple is going to keep growing?

Even the biggest companies slip up sometimes. One major screwup can happen, but two in a close time frame could indicate some real weakening in the armor.

The Apple Watch has been less than stellar in generating buzz, and since CEO Tim Cook did not want to talk sales numbers last week, that’s all we can go on.

And a strong case could be made that Apple missed the on-demand streaming market that Netflix seems to own.

Perhaps the billions Apple spent on developing a watch — when its best-selling product, the iPhone, eliminates the need for a watch — would have been better spent on building out Apple TV and/or buying Netflix.